The present invention relates to a package for a power semiconductor device for an equipment, such as intelligent power devices to be applied to inverters and other power conversion equipments.
First, reference is made to a VVVF inverter as an example, wherein a package structure and an equivalent network diagram for a conventional power semiconductor device using an insulated-gate type bipolar transistor (IGBT) as a power-switching device are shown in FIGS. 4(a) and 4(b). In FIG. 4(a), numeral 1 represents a package made from resin; 2 represents external main circuit terminals in a fasten tab terminal structure including direct-current input terminals P and N and alternating-current output terminals U, V and W; and 3 represents pin terminals for connection to a printed circuit board of an external control circuit 4. Inside the package 1, as shown in FIG. 4(b), incorporated are a three-phase bridge inverter circuit formed of six pairs of an insulated-gate bipolar transistor chip IGBT and a free-wheeling diode D, a gate-driving circuit (not illustrated), a protection circuit (not illustrated) and so on. The aforementioned terminals 2 and 3, which are connected to these circuits, are arranged on the upper surface of the package 1.
When applying such a power semiconductor device to an inverter, the aforementioned direct-current input terminals P and N of the external terminals 2 are connected to a direct-current source, and the alternating-current power terminals U, V and W are connected to an electric motor or other load. The printed circuit board of the external control circuit 4 is connected to the pin terminals 3 arranged on the package 1 directly or through a connector. Further, in order to suppress the surge voltage produced by the high-speed switching operation of the IGBTs, a snubber circuit 5 is externally connected between the direct current input terminals P and N.
The following problems arise in the aforementioned structure;
(1) The printed circuit board of the external control circuit 4 is connected to a row of pins made of a fine wire, so that the weight of the printed circuit board is entirely borne by one row of the pin terminals 3. Thus, the mechanically weak pin terminals 3 may be bent or broken when an external vibrational load or other load is applied. PA1 (2) The snubber circuit 5 is externally connected to the direct-current input terminals through lead wires, so that the wiring inductance of the leads is added between the input terminals and the snubber circuit. Thus, the snubber circuit is unable to adequately exhibit surge-voltage suppression effects. PA1 (1) On the upper surface of the package, support terminals for fixing the printed circuit board for the external control circuit are provided near the aforementioned rows of the pin terminals. PA1 (2) On the upper surface of the package, terminals for connection to the snubber circuit are provided, which are connected at the inside thereof to have the same potential as the aforementioned direct-current input terminals and drawn outwardly. PA1 (3) The support terminals described in the preceding paragraph (1) and the connection terminals for the snubber circuit described in the preceding paragraph (2) are both provided on the upper surface of the package. PA1 (4) In the structure described in the previous paragraph (3), the external main circuit terminals and the pin terminals are arranged on both sides of the upper surface of the package, while the support terminals are fitted at both ends of the row of the pin terminals, and the terminals for connection to the snubber circuit are formed near the direct-current input terminals.
In consideration of the above points, it is an object of the present invention to solve the aforementioned problems, and to provide a package for a power semiconductor device which is advantageous for connection to an external control circuit and a snubber circuit.